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Date: Fri, 12 Oct 2001 13:27:33 +1000
From: Rusty Russell <rusty@rustcorp.com.au>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: dipankar@in.ibm.com, linux-kernel@vger.kernel.org,
        paul.mckenney@us.ibm.com
Subject: Re: [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion
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On Wed, 10 Oct 2001 03:18:23 -0700 (PDT)
Linus Torvalds <torvalds@transmeta.com> wrote:

> 	lock
> 	unhash
> 	unlock
> 	if (atomic_dec()) {
> 		free
> 	}

And the read side is:
	lock
	loopup
	atomic_inc
	unlock

With RCU, read side is:
	loopup
	atomic_inc

Write is:
	lock /* protect against other writes */
	unhash /* be careful with wmb()s here... */
	unlock
	call_rcu(if (atomic_dec()) free) /* ie. does this later */

Clear?
Rusty.